For this thesis, a Japanese/English machine translation system with reversible
components has been designed and implemented in PROLOG. Sublanguage
co-occurrence patterns have been used to address the problems of lexical and
structural selection in the transfer between the internal representations of a
pair of natural languages. The system has been tested translating Japanese into
English in the domain of programming language manuals. The evaluation of
the test outputs provides some assessment of the utility of the
sublanguage approach as a method for the development and refinement of a machine
translation system. The thesis also explores the roles that a reversible
grammar would play in sharing linguistic knowledge between parsing and
generation.

The system has been developed with the goal of using sublanguage word
co-occurrence patterns to simplify the description of syntactic/semantic
knowledge needed in both the transfer rules and the analysis of the
source language.
In particular, sublanguage co-occurrence patterns are introduced to provide
semantic constraints and ellipsis recovery in parsing Japanese.

This thesis introduces a right-to-left parsing scheme for Japanese. The idea
for the right-to-left parsing algorithm evolved from the desire to produce
partial syntactic analyses of Japanese in a more deterministic manner than was
achieved by conventional left-to-right parsing schemes.
The algorithm makes efficient use of sublanguage co-occurrence patterns as
semantic knowledge to help disambiguate Japanese parses. The enforcement of
syntactic and semantic constraints is tightly interwoven during the course of
parsing. The performance in parsing Japanese has thereby been significantly
enhanced.

A procedure has been implemented for translating a Definite
Clause Grammar dually into a PROLOG parser and PROLOG generator, so that one
grammar can be used for parsing and generation. In current natural language
processing systems, separate grammars are used for parsing
and generation. However, there has long been an interest in
designing a single grammar for both parsing and
synthesis for reasons of efficiency and integrity, as well as
linguistic elegance and perspicuity. As part of the current implementation, a
strategy has been developed for creating efficient grammars for both
parsing and generation
using a goal reordering technique within the logic programming framework.